This is a simple expansion case for a battery pack, BNC Jack, Switches etc. for use in conjunction with the awesome (tr)uSDX Transceiver case by DL2MAN. It is fitted with modeled M3 Threads. to connect it just use longer M3 Screws (I test fit with M3x40).
It was build to spec for Stephan DC8LZ.
Best printed with Prusament PETG.
The author hasn't provided the model origin yet.